<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Responsive Navbar</title>
    <link href="https://cdn.jsdelivr.net/npm/tailwindcss@2.2.19/dist/tailwind.min.css" rel="stylesheet">
    <style>
        .nav-item {
            position: relative;
            transition: transform 0.3s ease, box-shadow 0.3s ease;
        }
        .nav-item::after {
            content: '';
            position: absolute;
            width: 100%;
            height: 2px;
            background: linear-gradient(90deg, red, green, blue);
            bottom: -4px;
            left: 0;
            transform: scaleX(0);
            transition: transform 0.3s ease;
        }
        .nav-item:hover::after {
            transform: scaleX(1);
        }
        .nav-item:hover {
            transform: scale(1.1);
            box-shadow: 0 0 10px rgba(255, 0, 0, 0.5), 0 0 20px rgba(0, 255, 0, 0.5), 0 0 30px rgba(0, 0, 255, 0.5);
        }
        .navbar {
            transition: box-shadow 0.3s ease;
        }
        .navbar:hover {
            box-shadow: 0 0 10px rgba(255, 0, 0, 0.5), 0 0 20px rgba(0, 255, 0, 0.5), 0 0 30px rgba(0, 0, 255, 0.5);
        }
    </style>
</head>
<body class="bg-gray-900 text-white">
    <nav class="navbar bg-gray-800 p-4">
        <div class="container mx-auto flex justify-between items-center">
            <a href="#" class="text-2xl font-bold">Brand</a>
            <ul class="flex space-x-4">
                <li><a href="#" class="nav-item px-3 py-2 rounded-md hover:bg-gradient-to-r from-white/10 to-white/20">Home</a></li>
                <li><a href="#" class="nav-item px-3 py-2 rounded-md hover:bg-gradient-to-r from-white/10 to-white/20">About</a></li>
                <li><a href="#" class="nav-item px-3 py-2 rounded-md hover:bg-gradient-to-r from-white/10 to-white/20">Services</a></li>
                <li><a href="#" class="nav-item px-3 py-2 rounded-md hover:bg-gradient-to-r from-white/10 to-white/20">Contact</a></li>
            </ul>
        </div>
    </nav>
</body>
</html>